Effect of underwater local cavity welding method conditions on diffusible hydrogen content in deposited metal

Abstract

One of the methods with great potential for applications in underwater repairs is local cavity welding. In local cavity method, cooling conditions and diffusible hydrogen amount in weld metal are nearly the same as those existed during welding in the air. This paper presents the results of literature survey and preliminary tests of the effect of local cavity welding conditions on diffusible hydrogen amount in a deposited metal. A Plackett -Burman design was applied to screen seven parameters: thickness of elastic cover, stick-out of electrode wire, welding current, voltage, travel speed of welding, salinity of water, and flow rate of shielding gas.

Cold Cracking of S460N Steel Welded in Water Environment

“…The water environment makes it impossible or difficult to apply many traditional methods for preventing cold cracking, which are successfully used in making welded joints in the air. Out of the methods lowering risk of cold cracking in water environment, the following find application in practice [3,7,23]:…”

Underwater Wet Repair Welding of API 5L X65M Pipeline Steel

“…It was caused due to the following factors : the relatively high value of carbon equivalent of the steel (0,41%), high cooling rate of the joint as well as high level of diffusible hydrogen in the welded joint. On the basis of the earlier conducted tests [16,21] it may be assessed that the diffusible hydrogen content in the deposited metal exceeded 35 ml/100g. Presence of polymer insulation was conducive to the lowering of width of the HAZ.…”

“…Direct contact of joined elements and electric arc with water contributes to occurrence of welding defects. The greatest problems are due to susceptibility to cracking, especially cold cracking, of welds made underwater [3,8,10,[13][14][15][16][17]. High cooling rate of welded joint and associated with it tendency to forming hard quenching structures within the HAZ and increased amount of diffusible hydrogen in deposited metal is conducive to the phenomenon [18][19][20][21][22].…”

Temper Bead Welding of S420G2+M Steel in Water Environment

“…Most general classification of underwater welding processes divide them into dry, wet and local dry cavity ones [1][2][3][4]. A characteristic feature of most commonly used wet welding is direct underwater contact of diver-welder, electrode and base material.…”